Fairy wrens with colorful feathers aren't more vulnerable than duller peers

April 2 (UPI) -- Brightly colored fairy wrens aren't more vulnerable to predation. Researchers found they are targeted as often as their duller peers.

Evolutionary biologists remain divided over the evolutionary origins of colorful plumage among female birds, but most assumed bright feathers increased the risk of being eaten.

When researchers at the University of Melbourne tested the theory, leaving both colorful and dull wren models exposed to predators in a variety of habitats. Colorful models were no more likely than dull models to be targeted by local predators.

"These findings do not support the long-standing hypothesis that conspicuous plumage, in isolation, is costly due to increased attraction from predators," researcher Kristal E. Cain said in a news release. "Our results indicate that conspicuousness interacts with other factors in driving the evolution of plumage coloration."

Scientists used magnets to stand 3D fairy wren models on small perches at a variety of test sites in natural wren habitats. The different sites varied in the thickness of vegetation, ranging from open savannah to dense forest. For the bird models, researchers deployed bright colored males, brightly colored females and dull females.

Fairy wrens, Malurus splendens, are a species of Australasian wren. Fairy wrens fall prey to larger birds, including kookaburras, butcherbirds, currawongs and goshawks.

Cameras helped scientists confirm that models detached from their perch had been attacked by predators. Researchers determined females were more frequently attacked than males, and birds in a habitat with sparser vegetation were more likely to be targeted.

"Our data suggest that adult birds living in open Australian habitats experience higher predation pressure than those in closed habitats, though it is unclear whether this pattern is due to differences in detectability, predator density, or both," Cain said.

The research was published this week in the journal The American Naturalist.

It's still possible that conspicuousness influences an animal's risk of predation, but that influence is likely mitigated -- or at least complicated -- by a variety of other factors, including gender, behavior and habitat.

"These conflicting patterns suggest that this relationship may be less straightforward than is often assumed and that explicit tests of the relationship between color and predation risk are required," Cain said.